The invention relates to an apparatus on a direct roving winder for contactless detection of the actual diameter of the roving package, in which the direct roving winder also has a machine frame with at least one winding spindle for the production of one or more roving packages and a cross-winding device.
The invention also relates to a method for controlling a roving winder, in which the package diameter is ascertained and the r.p.m. of the winding spindle is controlled depending on the package diameter ascertained. The invention also relates to a method for controlling an appliance for the spinning of glass fibres, in which a number of glass fibres are spun by means of a spinning nozzle and are wound onto a roving package by means of a direct roving winder.
In the production of roving packages the diameter of the package, which increases during the winding, is continuously detected and the r.p.m. of the winding spindle and the movement of the cross-winding device are controlled depending on the package diameter detected.
Mechanical scanning of the package surface and thus ascertaining the package diameter in direct roving winders is known. Such an apparatus for detecting the actual diameter of the package for synthetic threads is known from U.S. Pat. No. 6,076,760.
Controlling the r.p.m. of the winding spindle and the movement of the cross-winding device depending on different process-engineering-relevant data in direct roving winders in which essentially the package diameter is calculated from the winding time and the speed of the winding spindle is also known. This measure is known from U.S. Pat. No. 4,146,376. The speed of the winding spindle is controlled corresponding to an error signal which represents the deviation from a set value. During the start-up phase of the spinning appliance the signal is modified for compensation of temperature variations of the spinning nozzle.
A measuring device for the continuous measurement of the diameter of wound packages in warping machines which has a sensor which is designed as a wave transmitter/receiver, in which the diameter is measured from the time difference between the transmission of a wave impulse and the reception of the echo impulse is known from DE-A-38 10 414. A device which operates similarly for the measurement of a warp beam diameter in which the distance is measured by triangulation is known from DE-C-37 34 095.
A method for contactless detection of a package diameter in which the distance between the sensor and the package surface and the distance between the sensor and the spindle surface is detected and the package diameter is ascertained from the difference between the winding tube distance and the package distance is known from DE-A-199 60 285.
Ascertaining the residue of yarns located on a package by means of a sensor which measures the distance between the package surface and the sensor is known from JP Patent Abstracts of Japan 07 257 819. Ascertaining the package diameter by means of such a distance sensor and controlling the tension exercised on the threads depending on the package diameter ascertained is known from JP Patent Abstracts of Japan 00 185 879.
The object of the invention is to improve the titre uniformity within a roving package.
According to the invention this object is achieved in that the apparatus for contactless detection of the actual diameter contains a laser sensor which has a transmitter and a receiver for laser radiation, in which the distance of the laser sensor from the package surface is ascertained by means of the radiation from the sensor to the package surface and back to the receiver.
Through the contactless but direct detection of the package diameter, the r.p.m. of the winding spindle and the movement of the cross-winding device (distance of the cross-winding device from the package surface) can be controlled such that rovings of higher uniformity can be spun. While according to the state of the art the package diameter is calculated by means of different process-engineering data, in particular the r.p.m. of the winding spindle, the directly measured actual diameter of the roving package is used according to the invention for control of the r.p.m. of the winding spindle with the aim of producing rovings of very uniform titre. Accordingly, the invention also relates to a method for controlling a roving winder which has a machine frame, at least one winding spindle projecting from the machine frame, a cross-winding device pivotally joined to the machine frame and a device for ascertaining the momentary diameter of a package produced on the winding spindle, in which for the production of a package, rovings are guided via the cross-winding device onto the package and the distance of the cross-winding device from the package surface is controlled by means of the ascertained momentary diameter of the package. This method is characterized in that the momentary diameter of the package is ascertained by means of a laser sensor of the type mentioned above.
It is particularly advantageous to use the signals of the sensor for controlling the spinning nozzle temperature in order to combat variations of titre which occur. For this purpose the chronology of the actual diameter, i.e. the increase in diameter, is in particular taken into account. Consequently the invention also relates to a method for controlling a device for the spinning of rovings, in which the glass filaments spun by a spinning device are wound by means of a direct roving winder. This method is characterized in that the chronology of the actual diameter of the roving package, i.e. the increase of the diameter of the roving package, is ascertained by means of a laser sensor of the abovementioned type and the temperature of the spinning nozzle is controlled depending on the ascertained chronology of the actual diameter of the roving package.
Too fast an increase of the actual diameter of the package is a consequence of too high a nozzle throughput (bushing output) and thus of too high a titre. Through reduction of the spinning nozzle temperature the nozzle throughput and thus the titre can be reduced. The connection between increase of diameter and spinning nozzle temperature depends on a multitude of parameters and must be empirically ascertained for each system.
Usually two, three or four roving packages are produced on one winding spindle. Through a corresponding number of sensors the package diameter and the increase of package diameter can be separately monitored for each roving package. The signals of the sensors are used for recognition of diameter differences between the roving packages to be jointly wound on one winding spindle. If the diameter differences are too great, various measures can be taken:
The direct roving winder can be switched off in order to check spinning geometry, thread distribution and the like;
An automatic package change can be triggered in order to avoid the production of waste;
By means of prepared signals of the sensors the temperature balance of the spinning positions can be corrected.
Accordingly, the invention also relates to a method for monitoring the mode of operation of a direct roving winder, in which a plurality of roving packages are produced on one winding spindle and in which the package diameter is ascertained. The method is characterized in that the diameter of each roving package produced on the winding spindle is detected separately by means of a laser sensor of its own of the abovementioned type, and that the diameter values ascertained by the laser sensors for each winding spindle are compared with each other and a control signal is produced if the difference in diameter exceeds a threshold value.
The signals of the sensors also make possible a thread breakage check in that the growth of the roving packages is compared with a value for the minimum growth of the packages.
The sensors can be attached in stationary manner to the machine frame or be mounted on the cross-winding device so that they move with the latter.
The laser sensor can ascertain the distance to the package surface in known manner from the propagation time of the beam from the sensor to the package surface and back to the receiver. Taking into account the dimensions and constructional data of the direct roving winder and the known position of the laser sensor on the direct roving winder, the actual diameter of the roving package can be ascertained therefrom.
The distance of the laser sensor from the package surface is preferably ascertained by the known triangulation principle. The laser beam strikes the package surface as a small point and the receiver detects the position of this point in that it determines the angle at which the beam which returns from the point strikes the receiver. As the distance between transmitter and receiver and the angle at which the beam is sent out from the receiver are fixed values, the distance of the laser sensor from the package surface can be calculated from this. The receiver inside the sensor is a photodiode line or a PSD. The photodiode line is read by a built-in microcontroller. From the distribution of the beam returning from the point on the package surface on the photodiode line, the microcontroller calculates the angle exactly and from this the distance to the package surface. An OADM(trademark) laser distance sensor from WayCon Positionsmesstechnik GmbH, Inselkammerstr. 8, 82008 Unterhaching, Germany is suitable.
In direct winding of glass fibres or rovings under the spinning position, there is a danger of soiling the laser sensors, as dirt can be produced here by water and size (sticky substance) and also glass fibre fly. These substances and particles are whirled around by the air vortex produced by the rotating package and can within a very short time so severely soil the laser sensors that they break down. The laser sensor is therefore preferably arranged in a housing which has an opening for the passage of the laser beam, gas being blown in in the space between the laser sensor and the housing, which can exit from the opening. The penetration of these substances and particles and their deposition on the optics of the laser sensor is thereby prevented.
It is expedient for the opening to be provided with an attachment which has a drip course pointing away from the opening. This attachment ensures that projections of dirt forming over time do not come into the path of the beam, so that the laser beam can emerge unhindered. The attachment is easy to dismantle and can be easily cleaned as required. At the same time the optics of the laser can be cleaned through the opening in the housing.
It is possible to filter the signals of the laser sensor such that cleaning of the attachment is possible manually in the attached state and during normal operation. It has been shown that cleaning at intervals of 3 weeks is sufficient.